Methods of making them



Patented May 15, 1945 UNITED STATES PATENT OFFICE ORGANO- SILICON MAKINGTHEM METHODS OF Rob Roy McGregor,

New York No Drawing. Application June 10, 1941, Serial No. 397,468

12 Claims. (Cl. 260-2) trolled. The sihcane triols plastics, lacquers,and polymerization of or- A silicane triol containing the methylradicle, CH3Si(OH)-s, could theoretically yield a polymer containingsilicon equivalent to nearly 90% SiOz. Prior attempts to utilize suchcompounds have failed because, although the silicane triols condensemore or less readily by splitting ofi" water, it has not been possibleto control the reaction and the product ultimately becomes nonthesubstituted radicle The methyl compound, so readily by condensation thatthe triol has never been isolated and it is only with great diflicultythat complete oxidation can be brought about. It has been impossibleheretofore to obtain the condensed product as a heat convertible solidbecause by the time the solvent has been removed it has set to aninsoluble, infusible mass which cannot thereafter be worked and whichcracks when heated.

withstanding relatively high out decomposition.

Another object is to completely hydrolyze monosubstituted organo siliconcompounds Without loss of heat convertibility and solubility in organicsolvents.

Still another object is to control the polymerization of such hydrolyzedcompounds.

A further object is to polymerize and at the same time mold them underpressure.

POLmRS AND Swissvale, and Earl Leathen Warrick, Westview, P Glass Works,Corning, N. Y

asslgnors to Coming a corporation of REISSUED DEC 1 4 194 Another objectis to produce a soluble plastic containing condensed methyl silicanetriol.

Another object is to produce a pressure-molding powder containingcondensed methyl silicane triol.

Another object is to ing powder containing triol.

To these and other ends the invention comprises the methods and theproducts to be hereinafter more fully described andclaimed.

We have discovered a method by which the condensation of silicane triolsmay be controlled to yield a concentrated thermoplastic heat conproducea pressure-moldcondensed phenyl silicane and in some instances used inthe production of molding powders.

In practicing the invention a hydrocarbon radiclc of the class methyl,ethyl, propyl and phenyl hydrolysis, at least 1 mols of water per moleof the silicon compound, and in the case of the ester, an acid catalystsuch as dilute hydrochloric acid or oxalic acid is preferably included.Hy

drolysis of the ester ments yield the most desirable product.

Hydrolysis of the trihalide compound, for extrollable manner and, as inthe case of the trltotal hydroxyl groups and obtain a product whichethoxy compound, the condensation can be reis thermoplastic and whichcan be further polystrained to yield the desired product. Since the mriz d by heat. Analysis shows that in general reaction in the case ofthe trihalide compound is in their thermoplastic state the concentratedmore rapid than with the triethoxy compound 6 resins produced as abovedescribed possess on less time will be required to obtain the desiredthe average one hydroxyl group for each three product and it ispreferable to prevent any sub- Silicon oms- The general formula for ourstantial increase in temperature during the re- Product therefore pp arsto be [(RSiOhQQH],

where R is a hydrocarbon radicle, methyl, ethyl,

action by suitably cooling the reactants.

The solution containing the hydrolyzed and 10 propyl or phenyl. This maybe considered either partially condensed product is poured into about asa cyclic structure,

two volumes of water for the purpose of washing the product and themixture is stirred for about j R minutes. The catalyst, which if allowedto 1-0-31- remain would promote complete condensation is during thesubsequent treatment, is taken into solution and removed by the water.At the com- B on pletion of the washing, the mxture is allowed to settlefor about half an hour, or .for a time suflior as a cham Structure cientfor the desired product to separate out at R R B the bottom as a viscousand sticky liquid. The i Ai-O-Ai-Q-iwater is decanted, the product istaken up in a solvent such as acetone or benzene, and the solution isdried preferably by treatment with a These com r pounds are partiall dehdr dehydrating agent such as anhydrous sodium 2,, game sincic acidswhich e 031 18 orgamatregdiziie II it sulphate to remove residual water.Vacuum atta treatment may also be employed but requires an con igfg g gfi g gg g gy gz ggl i excesswe angoum i 23 g t otlherhdehydmmag group foreach three silicon atoms. Thei phzzgi agen 5 may e emp oye u on y t useare sui cal properties indicate that y represent a staable which areinsoluble in the solvent used and an which will extract free waterwithout causing giz zg gifigt efi ggt i th e i o fii ei e i :1 1?edcomfurther condensation of the product. The use monosmcane trims The Y9 Y t d of such a dehydrating agent at this point is a So caued B Stageiesms analogfms t0 the useful feature of the method, because without itsare hereinafter desi g convenience y use great care must be used laterto remove this 3. propy1 or phenyl silica anhydgg-lihyg, ethyl excesswater at low temperature. the Silicon content of the methylsmlgignaa151515 After separation of the sodium sulphate by dude is equivalent toabout 57 S02 ydecantation or filtration, the solvent is removed carboncontent is about 177 1 and fhe under reduced pressure with an air streamflowpercentages for the ethyl siolicic ig o dmg mg through the vessel,but not necessarily be about 71% S102 and 7 C f y 6 would through theliquid. The temperature is raised sincic anhydfide would be g 3 27 S?propyl gradually until evolution of gas from the liquid 37% C and forthe h 1 H v 02 and practically ceases and a sample of the liquid, wouldabout 467 8115555111010 anhydride when cooled to room temperature, isbrittle and The above i g' z; non-tacky. The temperature necessary toreach brepared in accordance fi smuted this state will vary directlywith the pressure concentrated form and g gg g 111 8 and should not beabove about 150 C. If the variety of uses They may be a pressure is notsufilciently reduced, the material vents and employed as he uer f willset up at a lower temperature to a partially ous materia1s After eva 5coatmg Variinsoluble and infusible mass. For the monothe coating may beg? i n the $1Vent methyl compound a pressure of about 100 mm. of andwill become infusible ggg gfiig g 353b e mercury is suitable. When theresin meets the above requirements, it is thermoplastic and heat 531: 3:i gi ig g gfjffg {TE- comfermble convertible and may then be poured outand alsubsequently polymerized b E0185 whlch e lowed to solidify. In thecase of the monophenyl They can also be ada g f ea compound,solidification requires longer treatpressure with heat despite g moldmgunder merit but may be hastened by additionally heatviscosity changeduring lairge ing for a short time at about 175 C. under Pressuremolding with heat requir es t l i ai gi atmosphenc pressure c sity mustfirst be increased sufliciently to 353 Monosubstituted compounds inwhich the subthe resins t stituted radicle is ethyl, propyl or phenyl,when high, viscositg iii c ofiii lgtg ilff li i l i ii from treated bythe above described process, yield quickly, and if the pressure is not aproducts having characteristics similar to the the right moment theresult t 8 a just monomethyl product. The ethyl and propyl dew andincohernt. g f gig gdis powcompounds oxidizemore readily than the methylcondensation which are fig gg cogilpoungo on geatintgd b formed duringheating must be eliminated b e a ve escri monosu stituted silicon causetrapped condensation product 1 resins probably do not have any doublebonds bubbles in the finished piec S res t m between silicon and oxygenbecause no instance w have found that gt of such a double bond is known.Hence polychanges can be avoided by the 1:22 d t merizationtheoretically can proceed until all with anhydrous boric oxide d thp aur hydroxyl groups have condensed and the silicon powder can be moldedwith ture as atoms are oined by siloxanelinkages. Such withoutobjectionable liquefaction and gessgre product would be infusible andunworkable. By evolution of gases. For this purpose th our method weprevent the condensation of the res n obtained by the controlled hydr li ggg condensation of the monosubstituted compound as described above ismilled to a line powder and is then mixed with a small amount, say about3%, of powdered anhydrous boric oxide. The mixture is allowed to standfor about 48 hours, whereupon the powder becomes non-liqueflable and maybe molded under pressure when heated to about 170 C. and results in asolid coherent mass free from bubbles and substantially transparent. Themolded mass is not only infusible but is insoluble in the usual organicsolvents. It contains the initially added boric oxide intimately andinvisibly dispersed throughout. So far as is known, boric oxide is theonly reagent which will produce this result. Other compounds, such asacetic anhydride, phthalic anhydride, phosphorus pentoxide and activatedmagnesium oxide, which it was expected would produce a similar result,were ineffective. These facts indicate that the boron is chemicallycombined. The mechanical strength and heat resistance of the molded massmay be improved by mixing a suitable filler with the molding powder. Anyof the fillers commonly employed with plastics may be used except thosehaving an alkaline reaction upon the molding powder, such as calciumcarbonate and the like. For example, we have used asbestos, glass fibresand glass flakes with satisfactory results. The composite molded massmay contain as much as 75% of the filler.

Although the most desirable molding powder is produced from themonomethyl resin by the in-- corporation of boric oxide, the monoethyl,monopropyl and monophenyl silicon resins will also produce some of thebenefits of our invention when so treated and are included within itsscope. The molding powders and moldings thereof produced in accordancewith this invention are characterized in that the resinous portion,whether it constitutes the total product or a part of a com positemixture, shows by analysis the presence of silicon, boron and an organicradicle which is methyl, ethyl, propyl or phenyl. The silicon expressedas SiOz, the carbon content and the ratio of silica to carbon for thevarious compounds will amount as follows: The polymer of which the meror structural unit contains the methyl radicle, (CH3SiO)aOOH, givesabout 85% $102, 17% C. and has a ratio The corresponding quantities forthe polymer containing the ethyl radicle are about 71% SiOa,

28% C. and

=2.5 for the propyl radicle about 61% $102, 37% C. and

cording to the above described process. The ethoxy silicanes containingone and two ethyl, propyl or phenyl radicles may be copolymerired inlike manner. Mixtures in which the disubstituted silicane contains adifferent radicle than the monosubstituted silicane may also bepolymerized. The product of such copolymerization possesses theadvantage of greater flexibility after complete polymerization than theproduct obtained from the treatment of the monosubstituted compoundalone. The characteristics of the copolymer resulting from suchcopolymerization are different than those of a mere mixture of theindividually polymerized monoand disubstituted compounds and a smallproportion of the product consisting of structural units having oneorganic radicle per silicon atom remains dissolved in the water whichwas employed for precipitating and washing the product. Hence the amountof the structural units having per silicon atom is somewhat amount whichwas contained ture before polymerization.

a mixture of 73 mol% of monomethyl triethoxy silicane and 27 mol% ofdimethyl diethoxy silicane is polymerized, the resulting polymercontains about 69 mol% of the monomethyl structure unit instead of the73 mol% which was presin the initial mix- For example, when ent in themixture before co-polymerization.

We claim:

1. A composition of matter which comprises a polymeric organo-siliconoxide having on the average less than two organic radicals per siliconatom, the organic substituents of said oxide being selected from theclass consisting of alkyl radicals of 1 to 3 carbon atoms and phenylradicals, and a minor proportion of boric oxide.

2. A molding powder which comprises a powdered thermosetting polymericorgano-silicon oxide having approximately one organic radical persilican atom, the organic substituents of said oxide consistingessentially of methyl radicals attached to silicon throughcarbon-silicon linkages, and a minor proportion of boric oxide.

3. A molding powder which comprises a powdered thermosetting polymericorgano-silicon oxide having approximately one organic radical persilicon atom, the organic substituents of said oxide consistingessentially of ethyl radicals attached to silicon through carbon-siliconlinkages, and a minor proportion of boric oxide.

4. A molding powder which comprises a. powdered thermosetting polymericorgano-silicon oxide having approximately one organic radical persilicon atom, the organic substituents of said oxide consistingessentially of phenyl radicals attached to silicon throughcarbon-silicon linkages, and a minor proportion of boric oxide.

5. A composition of matter which comprises a polymeric organo-siliconoxide having approximately one organic radical per silicon atom, theorganic substituents of said oxide being selected from the classconsisting of alkyl radicals of 1 to 3 carbon atoms and phenyl radicals,and a minor proportion of boric oxide.

6. A composition of matter which comprises a polymeric organo-siliconoxide having on the average less than two organic radicals per siliconatom, the organic substituents of said oxide consisting essentially ofmethyl radicals, and a minor proportion of boric oxide.

7. A composition of matter which comprises a polymeric organo-siliconoxide having on the average less than two organic radicals per siliconatom, the organic substituents of said oxide condiiierent than thesistlng essentially of ethyl radicals, and a minor proportion of boricoxide.

8. A composition of matter which comprisesa polymeric organo-siliconoxide having on the average less than two organic radicals per siliconatom, the organic substituents of said oxide consisting essentially ofphenyl radicals, and a minor proportion of boric oxide.

9. A molding powder which comprises a powdered thermosetting polymericorgano-silicon oxide having on the average less than two organicradicals per silicon atom, the organic substituents of said oxide beingselected from the class consisting of alkyl radicals of l to 3 carbonradicals and phenyl radicals, and a minor proportion of boric oxide.

10. A molding powder which comprises a powdered thermosetting polymericorgano-silicon oxide having on the average less than two organicradicals per silicon atom, the organic substituents of said oxideconsisting essentially of methyl radicals, and a minor proportion ofboric oxide.

11. A molding powder which comprises a powdered thermosetting polymericorgano-silicon oxide having on the average less than two organicradicals per silicon atom, the organic substituents of said oxideconsisting essentially of ethyl radicals, and a minor proportion ofboric oxide.

12. A molding powder which comprises a powdered thermosetting polymericorgano-silicon oxide having on the average less than two organicradicals per silicon atom, the organic substituents of said oxideconsisting essentially of phenyl radicals, and a minor proportion ofboric oxide.

ROB ROY McGREGOR. EARL LEATHEN WARRICK.

